Observation of Giant Band Splitting in Altermagnetic MnTe

Understand

We performed angle-resolved photoemission spectroscopy (ARPES) on hexagonal MnTe, a candidate for an altermagnet with a high critical temperature (TN=307 K).

• By utilizing photon-energy-tunable ARPES in combination with first-principles calculations, we found that the band structure in the antiferromagnetic phase exhibits a strongly anisotropic band-splitting associated with the time-reversal-symmetry breaking, providing the first direct experimental evidence for the altermagnetic band-splitting.
• The magnitude of the splitting reaches 0.8 eV at non-high-symmetry momentum points, which is much larger than the spin-orbit gap of ~0.3 eV along the GK high-symmetry cut.
• The present result paves the pathway toward realizing exotic physical properties associated with the altermagnetic spin-splitting.